Nice...that's a major improvement on the stock airbox. I'm a fan of the retro look as well.
Is your airbox from one of the small russian engines? I removed the red cowling from my engine, and it looks much better...less like a lawn mower
Opening up the intake has really made a difference on my bike. I love riding it now. The gear whine is either quietening down or maybe I'm just getting used to it.
Anyway, I'm becoming a fan of these 4 strokers.